1. Field of the Invention
This invention relates generally to systems, apparatuses, and methods for simulation and training using interactive computer graphics.
2. Description of the Relevant Art
In the past few years, computers have seen a significant increase in 3D graphical capabilities. Not surprisingly, interfaces capable of interacting with these complex 3D environments have started to move from laboratories to the enterprise and the consumer market as companies have begun to produce them in volume. While interfacing hardware has made significant advances, the accompanying software has lagged behind. This is not surprising considering the complexity involved in physically modeling computer-generated environments. Nonetheless, companies producing some of the less-complex interface hardware have introduced Application Program Interfaces (APIs) and Software Development Kits (SDKs) that facilitate the task of integrating their products into third-party applications.
Some of the hardware interfaces include force-feedback joysticks and steering wheels. Two companies which have introduced API's and SDK's for their joystick/steering wheel peripherals include Immersion Corporation and Cybernet Systems. Immersion markets its I-FORCE™ API, a programming interface that lets developers simulate various force-feedback effects such as: impacts, recoils, vibrations, springs, etc. It has been integrated into Microsoft's DirectX specification [4]. Similarly, Cybernet has introduced its CyberImpact™ SDK, with comparable features to Immersion's I-FORCE.
Another company that produces a haptic SDK is SensAble Technologies. SensAble markets a 3-degree-of-freedom (3DOF) force-feedback stylus called the PHANToM™ and their accompanying SDK is named Ghost™ [5]. Ghost is an object-oriented toolkit that represents the haptic environment as a hierarchical collection of geometric objects (spheres, cubes, cylinders, etc.) and spatial effects (springs, dampers, vibrations, etc.) The Ghost toolkit includes a spring model for presenting a single graphical point, as controlled by the PHANToM, from penetrating a graphical object. Noma and Miyasato propose a technique similar to Ghost, but also limit their technique to a single, non-articulated point [7].
Predictably, the first SDK's and API's to appear have been associated with relatively simple devices such as joysticks, steering wheels and 3D styli. In these cases, either the degrees of freedom of movement of the device are limited, or a single point is interacting with the environment. Not surprisingly, comparable software for whole-hand input interfaces has lagged behind because of the inherent complexity of the whole-hand interaction paradigm, with its multiple constraints and multiple, articulated degrees of freedom. Although whole-hand input devices present a greater challenge to integrate, they provide an extremely appealing advantage for interaction. What better way to manipulate complex virtual objects than to just “reach in and grab them?”
When trying to manipulate 3D objects, interfaces such as 2DOF mice, joysticks and styli quickly display their inherent limitations. However, users wearing instrumented gloves, or using some alternative hand-measurement system, if properly implemented, can manipulate digital objects just as they would in the real world. Up until a few years ago, these whole-hand software development efforts have resided in university and government laboratories. Examples include the work of Burdea et al. at Rutgers University using the Rutgers Master II [2], and the work of Coiffet et al., at the Laboratoire de Robotique de Paris, using the LRP Hand Master [1]. More recently, Luecke et al. have developed software to use an exoskeleton haptic device to apply virtual forces [3] and Thompson et al. [6] have used the Sarcos Dextrous Arm Master to perform direct parametric tracing on maneuverable NURBS models.
Commercially, two companies have introduced whole-hand software libraries. Virtual Technologies, Inc. has offered its VirtualHand® Software Library, while 5DT has offered an API for its DataGlove. Both let the user display a graphical hand on the screen that mimics the glove wearer's movement, but they do not provide manipulation capabilities; such capabilities are presently left to the user to develop. Inventive features of the subject invention include enhanced manipulation capabilities, the ability to prevent the virtual hand from penetrating grasped objects and virtual walls, and enabling dynamic interaction between the virtual hand and various controls.